Field of the Invention
The present invention relates to a surgical instrument, and more particularly to an improved rongeur surgical instrument having a mechanism to reduce the likelihood for breakage of the footplate and/or cutting mechanism thereof.
In surgical procedures, it is important to optimize treatment of the patient yet minimize the potential for breakage of the surgical instrument. One instrument used in certain surgical procedures is an instrument called a rongeur. A rongeur is a type of heavy-duty forceps for removing small pieces of bone, cartilage, or other tissue from the human body. Rongeurs are used, for example, in medical procedures performed on vertebrae of the back (i.e., laminectomy rongeurs). Laminectomy rongeurs are specifically designed to remove the lamina of the spine. The lamina is a bony plate that protects and covers the spinal cord.
A rongeur typically includes a frame comprising a barrel supported at a proximal end by a pistal-shaped grip. A footplate or cutting anvil is mounted at the distal end of a shaft disposed within the barrel. In at least one embodiment, the barrel, having a cutting blade at its distal end, is positioned for reciprocating axial movement from a first position to a second position (wherein the cutting blade is in contact with the footplate). The reciprocating movement of the cutting blade is provided by squeezing a trigger mechanism, such as a pull handle that is pivotally mounted to the frame of the rongeur. Small segments of bone or tissue may be removed by placing the same in an aperture formed in the barrel between the cutting blade and the footplate and then squeezing the trigger.
The underside of the lamina is in very close proximity to the spinal cord and nerve roots. It will therefore be understood by those skilled in the art that the footplate of the rongeur must be very thin so that can it fit between the patient's lamina and nerve structure. It will also be understood by those skilled in the art that, because the footplate is thin, it is susceptible to breakage when excess pressure is transferred from the trigger mechanism to the cutting blade. This may occur, for example, when the subject portion of a bone that is encountered is of a hardness or thickness that may not be cut by the rongeur without breakage of the footplate. Breakage of the footplate is therefore a matter of serious concern for the surgeon.
Accordingly, it is an object of the present invention to reduce the potential for breakage of the footplate.
It is a further object of the present invention to reduce the transfer of excess force to the footplate.